1. Field of the Invention
The present invention relates to an image forming apparatus.
2. Related Background Art
Flat panel image forming apparatuses, typically plasma display and liquid crystal display, are now being developed to make them thin and light in weight. A means for cooling an image display panel of such image forming apparatuses of high output and high precision has been proposed in order to prevent shortening element life due to a slow leak through a crack which would be formed without cooling, and deformation of the panel to be caused by thermal strain and to prevent a shortened lifetime to be caused by a temperature rise.
For example, as shown in FIG. 21, in the publication of JP-A-03-196782, a heatsink plate 51 having a fin structure is mounted on the back of an image display panel 10 in order to cool the back.
As shown in FIGS. 22A and 22B, in the publication of JP-A-08-179836, a metal pipe 61 is mounted on the back of an image display panel 10 and liquid cooled with an air fan 63 and a heatsink 62 is flowed in the metal pipe.
Also as shown in FIG. 23, in the publication of JP-A-08-055567, air blown from a fan 71 mounted on the back of a housing 72 is guided into the inside of the housing 72 along an image display panel 10 to the front side thereof, in order to cool the entire panel 10.
The above-described conventional techniques are found, however, not satisfactory, because the cooling system becomes bulky as the screen size becomes large and because the depth size and consumption power of the apparatus increase.
It is an object of the present invention to provide an image forming apparatus having the structure capable of efficiently dissipating heat not suitable for the apparatus.
It is another object of the present invention to provide an image forming apparatus having the structure capable of making uniform the distribution of temperature in the entire envelope (display panel) as much as possible.
It is another object of the present invention to provide an image forming apparatus capable of forming an image having a higher quality.
In order to achieve the above objects of the invention, there is provided an image forming apparatus which has an envelope formed by first and second substrates disposed at a predetermined distance therebetween and image forming means disposed in the envelope, wherein a heat insulating member is disposed on a surface of the envelope in an area excepting partial surface areas of the first and second substrates.